This beautiful city in the picture is Eugene, Oregon. Known for its Willamette Valley and the founding of athletic shoe giant Nike, it also had America’s worst air quality in 2022, according to the latest data from the Environmental Protection Agency. 

How Bad Was the Worst Day of The Year in Eugene?

Really bad! The World Health Organization’s annual limit for tiny particles in the air (called “PM2.5”) is 5 micrograms (µg/m3). On Eugene’s worst day, the air had 247 micrograms. 

Over 2022, Eugene averaged 23.3 micrograms. That’s over 4 times the WHO annual limit. In the US, average PM2.5 is 1.8 times WHO’s air quality guideline.

Eugene’s annual average PM2.5 is 40% higher than the second most polluted city, Bakersfield, California. On its worst day, Eugene’s PM2.5 was 375% higher than Bakersfield’s.

Date source: EPA 2022 Air quality data -cbsafactbook2022

Why On Earth Is Eugene So Polluted? 

Wildfire In Lane County

In 2022, wildfire smoke contributed to the high air pollution in Lane County. The Cedar Creek Fire ignited in August, 2022, in the Willamette National Forest, about 50 miles (80 km) southeast of Eugene. In just three months, the fire grew to 127,283 acres. 

Winds carried Cedar Creek’s smoke as far as Seattle, 250 miles (400 km) northward, causing it to become the most polluted metropolitan city in 2022. Smoke also invaded Eugene, making the PM2.5 shoot to 7 times the WHO limit in October 2022.

Read more: How Far Can Wildfire Smoke Travel?

The graph below shows that Oregon’s cumulative PM2.5 for 2022 (purple line) were lower than 2021 (blue line). But Eugene had the opposite trend. The city’s PM2.5 for 2022 noticeably surpassed 2021.

Grass Seed Industry in Oregon

The Willamette valley’s temperate, wet winters and dry summers provide optimal conditions to grow grass seed. Ninety percent of grass seed production in Oregon is located in the Valley and occupies nearly a quarter of the area.

Here comes the problem: 3.75% of Oregon’s grass seed fields are burned to kill pests and their eggs. Although the practice is highly regulated, it inevitably creates smoke and increases PM2.5.

The grass industry also creates pollen, which has consequences for residents with allergies. Many require medical assistance to make it through the allergy season and when exposure to higher grass pollen levels can trigger asthma attacks.

Read more: Simple Trick to Reduce Pollen and Seasonal Allergy Symptoms

Wildfires are variable and hard to predict. Eugene will probably not remain America’s most polluted city. But the shock of hazardous air is a reminder of the danger wildfire smoke poses in a world increasingly beset by climate change.